The system takes real-time imagery of local obstacles, be they stairs, walls, or trees, as well as moving objects like cars and other people, and alerts the wearer using the sounds perfected in the Spanish echolocation system mentioned above.
The helmet uses stereo headphones to denote where the objects are relative to the wearer, and the volume of the sound indicates the distance. The device has a 60-degree range of vision, and can identify objects as far away as 15 feet. The researchers are also currently looking to integrate GPS data into the rig, so that users can use it to plot specific courses.
http://www.popsci.com/scitech/article/2009-08/navigation-helmet-creates-sound-maps-blind